M*CARBO Brotherhood

How does firing pin work?

Just curious. I completed the trigger job, and can easily see how the trigger + trigger bar + sear + hammer are working. What I am not so sure about is how the bolt and firing pin function, and I am just curious. I have tried to dry fire with the firearm collapsed, but I do not see/feel the firing pin activate on trigger pull, though I am not sure it’s supposed to. I have been able to find animations for AR15 and various pistols, but they don’t seem to be too similar.

This is not important, just for my own curiosity. Does anyone know of other firearms with similar mechanics which might have more diagrams or animations available to teach an old dummy?


The trigger releases the sear using the trigger bar. That releases the hammer which swings up into the slot in the bolt head and strikes the back of the firing pin, which then moves forward and hits the primer of the cartridge. The firing pin spring pushes the firing pin back so when the next round is chambered, it won’t be sticking out and slam-fire.

Meanwhile, the bolt head and bolt are pushed to the rear by blowback, extracting and ejecting the spent case, recocking the hammer, and getting ready for the next trigger pull. When the recoil spring pushes the bolt and bolt head forward again, a new round is stripped from the magazine and pushed into the chamber.

During this whole process, the trigger bar is cammed down so it doesn’t re-engage the sear - this is so the weapon is semi-auto instead of auto - and when you release the trigger, the trigger bar moves back into position and you’re ready to fire again.

For excellent animations of the internal workings of lots of firearms, you might like World of Guns Gun Disassembly. There’s a version on Steam, and the original was on http://noble-empire.com


@hash_tables Welcome to the Brotherhood.


Thanks both, that was a great explanation. I am glad to be here!


Sorry @hash_tables, I forgot to say welcome to the brotherhood.


For all practical purposes with a hammer fired weapon the hammer strikes the firing pin and discharges the gun. Examples would be the AR15 the Czech VZ58, or the Kalashnikov 47. Striker fired weapons would for all practical purpose include most bolt action rifles such as the K98, Springfield 03 and Enfield. In the realm of handguns the CZ75 family, the 1911, and most of the older Smith and Wesson pistols were hammer fired. The Glock, the later iterations of the Walthers, and most of their progeny such as the currrent Sigs are striker fired. Is one better than another? Well there is always a trade off … One may function more effectively in one situation but in a different application maybe not so much. As someone once said… Ya pays yer money and ya takes yer chances. If it works for you it works. Probably no help at all but…that’s guns! L